My Sig 1/4 scale Cub, comes in at 17 lbs. I fly it hard sometimes, but, throttle back and fly scale too. I have a ST 3250 in the nose swinging a 18 x 6 beechwood prop at almost 10000 rpm. It will not sustain a hover, but, comes close.

I always recommend plenty of power, just be careful of when and how you use it. I would go with a 35cc or larger.

Just my HO.